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MDEV-9676: RANGE-type frames for window functions

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- Handle ORDER BY DESC in window definitions.
- Fix an issue in Frame_range_current_row_top
This commit is contained in:
Sergei Petrunia
2016-03-14 14:13:59 +03:00
parent b8d8d9b8cc
commit ce8a0d8e19
3 changed files with 208 additions and 20 deletions
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73
sql/sql_window.cc
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@ -275,9 +275,9 @@ public:
{
int rc= read_record->table->file->ha_rnd_pos(read_record->record, p);
if (!rc)
return true;
return true; // restored ok
}
return false;
return false; // didn't restore
}
// todo: should move_to() also read row here?
@ -409,6 +409,11 @@ class Frame_range_n_top : public Frame_cursor
Item *item_add;
const bool is_preceding;
/*
1 when order_list uses ASC ordering
-1 when order_list uses DESC ordering
*/
int order_direction;
public:
Frame_range_n_top(bool is_preceding_arg, Item *n_val_arg) :
n_val(n_val_arg), item_add(NULL), is_preceding(is_preceding_arg)
@ -422,9 +427,18 @@ public:
DBUG_ASSERT(order_list->elements == 1);
Item *src_expr= order_list->first->item[0];
if (order_list->first->direction == ORDER::ORDER_ASC)
order_direction= 1;
else
order_direction= -1;
range_expr= (Cached_item_item*) new_Cached_item(thd, src_expr, FALSE);
if (is_preceding)
bool use_minus= is_preceding;
if (order_direction == -1)
use_minus= !use_minus;
if (use_minus)
item_add= new (thd->mem_root) Item_func_minus(thd, src_expr, n_val);
else
item_add= new (thd->mem_root) Item_func_plus(thd, src_expr, n_val);
@ -458,7 +472,7 @@ public:
*/
if (cursor.restore_last_row())
{
if (range_expr->cmp_read_only() <= 0)
if (order_direction * range_expr->cmp_read_only() <= 0)
return;
item->remove();
}
@ -470,7 +484,7 @@ private:
{
while (!cursor.get_next())
{
if (range_expr->cmp_read_only() <= 0)
if (order_direction * range_expr->cmp_read_only() <= 0)
break;
item->remove();
}
@ -487,6 +501,8 @@ private:
Bottom end moves first so it needs to check for partition end
(todo: unless it's PRECEDING and in that case it doesnt)
(todo: factor out common parts with Frame_range_n_top into
a common ancestor)
*/
class Frame_range_n_bottom: public Frame_cursor
@ -502,6 +518,12 @@ class Frame_range_n_bottom: public Frame_cursor
Group_bound_tracker bound_tracker;
bool end_of_partition;
/*
1 when order_list uses ASC ordering
-1 when order_list uses DESC ordering
*/
int order_direction;
public:
Frame_range_n_bottom(bool is_preceding_arg, Item *n_val_arg) :
n_val(n_val_arg), item_add(NULL), is_preceding(is_preceding_arg)
@ -516,8 +538,18 @@ public:
DBUG_ASSERT(order_list->elements == 1);
Item *src_expr= order_list->first->item[0];
if (order_list->first->direction == ORDER::ORDER_ASC)
order_direction= 1;
else
order_direction= -1;
range_expr= (Cached_item_item*) new_Cached_item(thd, src_expr, FALSE);
if (is_preceding)
bool use_minus= is_preceding;
if (order_direction == -1)
use_minus= !use_minus;
if (use_minus)
item_add= new (thd->mem_root) Item_func_minus(thd, src_expr, n_val);
else
item_add= new (thd->mem_root) Item_func_plus(thd, src_expr, n_val);
@ -560,7 +592,7 @@ public:
*/
if (cursor.restore_last_row())
{
if (range_expr->cmp_read_only() < 0)
if (order_direction * range_expr->cmp_read_only() < 0)
return;
item->add();
}
@ -578,7 +610,7 @@ private:
end_of_partition= true;
break;
}
if (range_expr->cmp_read_only() < 0)
if (order_direction * range_expr->cmp_read_only() < 0)
break;
item->add();
}
@ -695,7 +727,6 @@ class Frame_range_current_row_top : public Frame_cursor
Group_bound_tracker peer_tracker;
bool move;
bool at_partition_start;
public:
void init(THD *thd, READ_RECORD *info,
SQL_I_List<ORDER> *partition_list,
@ -709,31 +740,33 @@ public:
void pre_next_partition(longlong rownum, Item_sum* item)
{
// fetch the value from the first row
// Fetch the value from the first row
peer_tracker.check_if_next_group();
}
void next_partition(longlong rownum, Item_sum* item)
{
at_partition_start= true;
cursor.move_to(rownum+1);
}
void next_partition(longlong rownum, Item_sum* item) {}
void pre_next_row(Item_sum* item)
{
// Check if our current row is pointing to a peer of the current row.
// If not, move forward until that becomes true.
// Check if the new current_row is a peer of the row that our cursor is
// pointing to.
move= peer_tracker.check_if_next_group();
}
void next_row(Item_sum* item)
{
bool was_at_partition_start= at_partition_start;
at_partition_start= false;
if (move)
{
if (!was_at_partition_start && cursor.restore_last_row())
/*
Our cursor is pointing at the first row that was a peer of the previous
current row. Or, it was the first row in the partition.
*/
if (cursor.restore_last_row())
{
// todo: need the following check ?
if (!peer_tracker.compare_with_cache())
return;
item->remove();
}